86Rb+ transport in Leishmania infantum promastigotes under various in vitro culture conditions.
The survival of Leishmania, which encounter drastic changes of environment during their life-cycle, requires regulation and control of ionic concentrations within the cell. We analysed the influence of growth stage, ionic composition of the medium, heat and acidic stress on 86Rb+ influx in L. infantum promastigotes. Proliferating promastigotes exhibited faster and higher 86Rb+ uptake than stationary cells. Cl- anion did not have any effect, but in the presence of physiological concentration of HCO3-, 86Rb+ uptake was significantly increased. This enhancing effect was only partially inhibited by N,N'-dicyclohexylcarbodiimide (DCCD), a blocker of ion-translocating ATPases. 86Rb+ influx was abolished by N-ethylmaleimide (NEM), indicating a major contribution of plasma membrane transporters. Heat shock and acidic shock notably decreased 86Rb+ influx. Our data provide indirect evidence that an energy-dependent system which brings K+ in, such as K+/H(+)-ATPase evidenced by Jiang et al. (1994), is active in Leishmania in different environments. Mechanism(s) other than ion-translocating ATPases occur, at least in the presence of HCO3-, and their contribution to K+ pathways varies in different environmental conditions.
Suffia
I
I
Laboratoire de Parasitologie, Faculté de Médecine, Nice, France.
Schmid-Antomarchi
H
H
Kubar
J
J
D000143:Acids; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D000001:Calcimycin / Q000494:pharmacology; D003470:Culture Media; D004734:Energy Metabolism; D018869:Heat-Shock Response; D007038:Hypotonic Solutions; D017136:Ion Transport / Q000187:drug effects; D018314:Leishmania infantum / Q000254:growth & development / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D012414:Rubidium Radioisotopes
D000143:Acids; D001639:Bicarbonates; D003470:Culture Media; D007038:Hypotonic Solutions; D012414:Rubidium Radioisotopes; D000001:Calcimycin; D000251:Adenosine Triphosphatases; D011188:Potassium